Combine the Dijon mustard, honey, white wine vinegar, salt, and garlic powder in a medium bowl and whisk until smooth and fully blended. With the whisk moving constantly, slowly pour in the vegetable oil in a thin, steady stream to emulsify the dressing into a creamy, cohesive consistency. Split the dressing evenly into two portions — transfer one half to a shallow dish to use as a marinade for the chicken, and set the remaining half aside to dress the finished salad.

Add the pounded chicken breasts to the shallow dish of dressing, turning to coat both sides thoroughly, and allow them to marinate for 30 minutes at room temperature. Heat a large skillet over medium-high heat until hot. Lift the chicken from the marinade, letting any excess drip off, and cook for 5 to 8 minutes per side until deeply golden and cooked through to an internal temperature of 165°F. Move the chicken to a cutting board and rest for a few minutes before slicing into strips.

While the chicken cooks, build the salad base: spread the chopped romaine lettuce across serving bowls or a large platter. Arrange the cherry tomatoes, sliced red onion, diced avocado, crumbled bacon, and quartered hard-boiled eggs in separate, distinct piles or rows on top of the lettuce so each ingredient remains visible and the presentation stays organized.

Lay the warm sliced chicken strips over the arranged salad components. Drizzle the reserved honey mustard dressing evenly across the entire salad, coating all the toppings. Scatter the feta cheese crumbles over the top and finish with freshly cracked black pepper to taste. Serve right away while the chicken is still warm.